Hydration refers to the measure of water content in the body tissues. Water makes up a large proportion of the human body; approximately 60% in adult men and 55% in adult women. Almost all physiological processes are impacted by our hydration status, including regulation of body temperature and transport of oxygen and nutrients to the cells. Dehydration resulting from the failure to adequately replace fluids can lead to inadequate dissipation of heat, which may result in an elevation of core body temperature and excessive cardiovascular strain. Thirst is not necessarily an accurate indicator of hydration status, as water has been found to quench the sensation of thirst before adequate body fluid replacement is achieved. Ambient temperature and humidity, as well as weight and activity level, contribute to an individual's hydration status at any given time.
Research suggests that fluid consumption in general and water consumption in particular can have an effect on the risk of urinary stone disease; cancers of the breast, colon, and urinary tract; childhood and adolescent obesity; mitral valve prolapse; salivary gland function; and overall health in the elderly. However, in hospitals it is frequently vital to maintain the rate of hydration of a patient. In some cases, the rate of hydration is partially known by the rate of delivery of intravenously supplied fluids. In the past, the patient's total oral consumption of fluid has been monitored and maintained by guesswork. Patient care is often deficient, however, because there is no accurate measure of the patient's rate or quantity of hydration. This results in patient upsets and increases time and effort required by the medical staff.
There exist many instances where a liquid in a container is to be dispensed repeatedly in the same, pre-measured quantity. One such situation is the dispensing of a liquid to a user in a medical or assisted living environment, e.g., home care, nursing home, hospital, etc. In the foregoing settings, there have typically been two different methods for dispensing exactly-repeated quantities of a liquid to a user. The first method includes carefully pouring the liquid into a measurement container to obtain the desired amount, then having the person drink. The chief disadvantages of this method are that an additional tool, the measurement container, must be provided and the fluid has to be manually poured into the containers increasing the chances of spillage and incorrect measurements.
A second method includes controlling the outlet of a liquid container by a tap and measuring the dispensed amount of liquid by reading the liquid level on a scale on the liquid container. Because the liquid container has to be held exactly vertical in order to correctly read the level of the liquid, and since at least one hand is needed in order to control the tap, this method is mainly restricted to liquid containers installed at a fixed location and is not convenient for small transportable bottles in an assisted care setting. Moreover, there is no record of refills with this method, and therefore it is often difficult to accurately determine the total consumption of liquid dispensed. Additionally, at least a part of the container needs to be transparent in order to observe the level of liquid. One other prevalent problem associated with such methods is the eventual warming and stagnation of the fluid. This causes the liquid to be less than desirable for ingestion by a person.
Various liquid containers for supplying drinking water are commercially available. Sigdell et al., in U.S. Pat. No. 3,919,455 (1975) teach an apparatus which measures the volume and flow rate of liquids. This system uses a siphon-suction principle in which a container is filled by suction, then when a predetermined level is reached, a siphon causes the container to drain. Electrical sensors detect the evacuation of the water in the container and transmit a signal that the container is ready for another fill-and-drain cycle. While this system provides information about liquid volume dispensed, it does not display the volume dispensed as a function of time. Further, suction is used only to fill the chamber. If the siphon action is not allowed, the chamber will not drain and the chamber will remain full. Even if repeated siphon and suction cycles were employed, this system would not be practical in human hydration applications. The entire contents of the container are drained in each siphon cycle. Thus, the user would be required to swallow the entire volume of the container. Because of the container's fixed size, it would not be possible for the user to withdraw a single sip of liquid at one time, and at a later time withdraw a mouth-full from the same container. Because of these limitations, this system is not applicable to maintenance of hydration.
In U.S. Pat. No. 6,212,959, issued to Perkins, and incorporated herein by reference, a system is provided for insuring proper human hydration that includes an oral-suction-activated flow meter that measures and displays the volume of fluid withdrawn from a reservoir through tubing. An optional check valve prevents return flow of fluid from the user's mouth to the reservoir. Mode and control buttons control operation of a microprocessor and a display. Both alphanumeric and graphical displays show the volume withdrawn as a function of time or other events. Drink reminder alarms are provided through a display or loudspeaker to alert the user when it is time for a drink to ensure proper hydration.
None of the prior-art fluid supply systems accurately reports the rate or quantity of fluid consumption. Further, none of the prior-art fluid supply systems indicates, in advance of the user's thirst, that it is time to consume more fluid. By the time a user is thirsty, she or he is already partially dehydrated.